Direct positive photographs from hydrazine-containing developers



Patented Aug. 7, T951 DIRECT POSITIVE PHOTOGRAPHS FROMHYDR-AZINE-CONTAINING DEVELOPERS Charles E. Ives, Rochester, N. Y.,assignor to Eastman Kodak Company, Rochester, N. Y., a corporation ofNew J ersey No Drawing. Application Aprii 29, 1950, Serial No. 159,150

7 Claims.

Thisinvention relates to photography and particularly to a method ofmaking direct positive photographs.

In Fallesen U. S. Patent 2,497,875, a method is described for makingdirect positive photographs with an internal latent image type emulsionby developing the exposed emulsion in an aerial fogging developer withaccess of oxygen.

I have now found a method for developing direct positive images in anexposed internal latent image emulsion which does not requireformaldehyde and which, therefore, has better keeping properties thandevelopers hitherto used for this purpose. In addition, the developerswhich I propose to use do not require the addition of oxidizin agents orany special areation technique for production of the positive image.

According to my invention the internal latent image emulsion is exposedand placed directly in a silver halide developing solution containing ahydrazine compound of the general formula in which at least two Rs arehydrogen atoms and when less than four Rs are hydrogen atoms, theremaining Rs are aryl, aralkyl, acyl, or carboxylic acid amide groups.Preferably, the hydrazine compound does not contain more than onearalkyl, acyl, or carboxylic acid amide group, although it may containeither one or two aryl groups.

The photographic emulsion used in the process of my invention is agelatino-silver halide emulsion such as a silver bromide emulsion, asilver bromoiodide emulsion or a silver chloroiodide emulsion. It neednot contain optical sensitizing dyes although certain sensitizing dyesmay be added to it for the purpose of optical sensitizing or forpromoting reversal. The emulsion should be undigested or if digested,the digestion should be carried out without the use of sulfursensitizers. as Burtons emulsion, described in Wall, PhotographicEmulsions, 1929, pages 52 and. 53. Burtons emulsion is made as follows:

Silver nitrate g 100 Water cc 500 Ammonia-to form clear solution.

B Potassium broinid'e g 80 Potassium iodide g 50 Soft gelatin g 20 Watercc 1000 C Dry gelatine g 250 An emulsion of this type is that known 2 Bis heated to 70 C. and A, cold, added to B with constant shaking,digested for 20 minutes .at 50 C., and allowed to cool slowly. C isadded after being allowed to swell for 20 minutes in water, drained andmelted. The emulsion is then set and washed.

An internal latent image emulsion, that is, one which forms the latentimage mostly inside the silver halide grains, as described on pages 296and 297 of Mees The Theory of the Photographic Process, 19%2, isespecially useful for the process of my invention.

Most of the internal latent image emulsions are silver promo-iodideemulsions of high iodide content, preferably containing at least l0%20%of iodide. Burtons emulsion is an emulsion of this type, having a silveriodide content of approximately of the content of silver halide. It isnot absolutely essential, however, for the emulsion to contain silveriodide.

An internal latent image emulsion made as described in Davey and KnottU. S. application Serial No. 82,914, filed March 22, 1949, may also beused according to my invention. This emulsion is prepared by firstforming in the absence of ammonia and in one or more stages silver saltgrains consisting at least partly of a silver salt which is more solublein water than silver bromide, subsequently convertin the grains tosilver bromide or silver bromoiodide and if the silver iodide content ofthe emulsion is less than 6% calculated on the total silver halide,treating such grains with an iodine compound to bring the silver iodideup to at least 6%, ripening preferably in the absence of ammonia andthen either washing out some of the soluble salts or washing out theWhole of the soluble salts, followed by the addition of soluble saltssuch as soluble chloride or bromide. An example of an emulsion made inthis way is as follows:

Solution No. 1:

Inert gelatine grams 2 0 KCl dour- 20] at 40 C. Water lcc 560 SolutionNo. 2:

KCl gi'ams 100 a Water "cc." 52ml Solution No. 3: I

AgNOs "grams; 195 0 Water cc 520)} Solution No. 4:

KBr "grams; 160 KI do 40] at 45 0. Water cc 500 Run solutions Nos. 2 and3 simultaneously into solution No. 1 in a vessel, taking seconds to dothis. Then ripen for 1 minute at 45 C. Next add solution No. 4, thenripen for 20 minutes at 45 C. Next add 235 grams of inert gelatine(dry). Then ripen at 45 C. for 15 minutes during which time the gelatinedissolves. Set and shred the emulsion and then wash until free from allsoluble bromide and then add about 150 cc. of 10% solution of KCl (byweight), and then add water to make 3 /2-1itres.

An internal latent image type of silver halide emulsion may be definedas one which, when a test portion is exposed to a light intensity scalefor a fixed time between A and 1 second, and developed for 4 minutes at20 C. in the ordinary, surface developer (Example I), exhibits a maximumdensity not greater than /5 the maximum density obtained when the sameemulsion is equally exposed and developed for 3 minutes at C. in aninternal type developer (Example II). Preferably the maximum densityobtained with the surface developer is not greater than lie the maximumdensity obtained when the same emulsion is developed in the internaltype developer. Stated conversely, an internal latent image emulsion,when developed in an internal type developer (Example II) exhibits amaximum density at least 5, and preferably at least 10, times themaximum density obtained when the same emulsion is exposed in the sameway and developed in a surface developer (Example I).

My process is carried out by exposing the internal latent image emulsionlayer to an object or image and then placin the exposed emulsion layerdirectly in a silver halide developing solution containing one or moreof the hydrazine compounds. Developing agents suitable for use in theprocess of my invention include the usual phenolic or aminophenol typedeveloping agents, such as N methyl p aminophenol sulfate, pbenzohydroquinone, catechol, Z-methyl hydroquinone,2-chlorohydroquinone, p-aminophenol, and. pyrogallol. The developingsolution should have a pH of from 10 to 13, depending upon the degree ofactivity of the particular hydrazine compound which it contains,although the preferred range with most hydrazine compounds is from pH 11to pH 12.

The following hydrazine compounds are suitable for use according to myinvention:

NHzNHz-2H C1 Hydrazine dihydrochloride Phenylhydrazine hydrochloridep-Bromphenylhydrazine hydrochloride p-Chlorphenylhydrazine hydrochloride2,5-dichlorophenyl hydrazine p-Tolyl hydrazine hydrochloride p-Toluenesulfonyl hydrazine a-Naphthylhydrazine p-Acetylphenylhydrazinea-Benzyl-a-phenylhydrazine hydrochloride C H11CH-C O NHNHi CH2C ONHNHzn-Arnyl succinyl dihydrazide NaSO3CH-C ONHNH:

CH2-O ON HNHz Sodium sulfosuccinyl dlhydrazide NHC ONHNH; I THC ONHNHzHydrazine dicarbonic dihydrazide Hydrazobenzene HOOC NHNH2p-Hydrazinobenzoic acid p-Hydrazinobenzene sulfonic acid (sodium salt)SOaNa Phenylhydrazine-m-sulfonic acid (sodium salt) omsomnomcmQ-zvnnm p-B- Methylsulfonamido) ethyl] phenyl hydrazine B-Phenyl acethydrazidopyrldiniurn chloride N=COH ddition product of phenyl hydrazine and1-phenyl-3- ,hydroxy-5-pyrazolone of probable structure shown N,Ndiphenyl hydrazine p-Diphenyl hydrazine cummnnOOnnnmnmp,p-Dihydrazino-dipheny1-dihydrochloride NH O O NHNB:

NH C O NE NH:

4-p-phenylene disemicarbazide An ordinary, surface-type developer, thatis, one which develops an image only on the surface of the grains of aninternal latent imageemulsion, is the following:

Example I p-Hydroxyphenylglycine g Sodium carbonate (crystals) g 100Water .to liter 1 Development time, 4 min. at C.

An internal type developer, that is, one which develops an image insidethe grains of an internal latent image emulsion, is the following:

Example II Hydroquinone g 15 Monomethyl-p-aminophenol su1fate -g 15Sodium sulfite (anhydrous) r g 50 Potassium bromide -g 10Sodiumhydroxide g Sodium thiosulfate (crystals) g 20 Water to liter 1Development time, 3 min. at 20 C.

My invention will be further described by ref erence to the followingspecific example:

Example In An emulsion made as described in the Davey and Knottapplication Serial No. 82,914. was coated on a support, dried andexposed on an intensity scale sensitometer to 3000 Kelvin tungstenillumination and developed for 3 minutes at 70 F. in a solution of thefollowing compositions:

N-methyl-p-aminophenol sulfate g 5 Hydroquinone g 10 Sodium sulfite g 75Sodium metaborate g Sodium hydroxide g 10 Phenyl hydrazine hydrochloridew g 0.5 Water to liter 1 sulfonyl hydrazine, no reversal was obtainedwhen the 5-methyl benzotriazole was added to the developer. In somecases the reversal was weakened by adding the benzotriazole. In othercases the maximum density was increased by adding 5- methylbenzotriazole to the developer, for example, with phenyl hydrazine or p-[5- (methylsulfonamido) ethyl] phenyl hydrazine.

Although the reversal effect obtained in my process does not requireagitation of the developer or the presence of oxidizing agents, Ibelieve that the fogging action obtained is related to aerial oxidation.The active agent, which is derived from the hydrazine compound appearsto have a long life in the developing solutions and only brief exposuresto atmospheric oxygen appear sufiicient to produce fogging even in theabsence of continued aeration. My process, therefore, has distinctadvantages for deep tank photographic processing.

It will be understood that the examples and modifications includedherein are illustrative only and that my invention is to be taken aslimited only by the scope of the appended claims.

I claim:

1. The method of obtaining a direct positive image in a silver halideemulsion layer which comprises exposing to light rays to which theemulsion is sensitive, a silver halide emulsion layer a test portion ofwhich upon exposure to a light intensity scale for a fixed time betweenM and 1 second and development for 3 minutes at 20 C. in the followinginternal type developer Grams Hydroquinone 15 Monomethyl-p-aminophenolsulfate l5 Anhydrous sodium sulfite 50 Potassium bromide 10 Sodiumhydroxide 25 Sodium thiosulfate 20 Water to 1 liter gives a maximumdensity at least 5 times the maximum density obtained when the equallyexposed silver halide emulsion is developed for 4 minutes at 20 C. inthe following surface developer (I) Grams p-Hydroxyphenylglycine 10Sodium carbonate Water to 1 liter and developing only the unexposedportion of said emulsion layer in a developer containing a hydrazinecompound of the general formula in which at least 2 Rs are hydrogenatoms and when less than 4 Rs are hydrogen atoms, the remaining Rs areselected from the class consisting of aryl, aralkyl, acyl and carboxylicacid amide groups, but not more than one B is any one of said aralkyl,acyl and carboxylic acid amide 7 V utes at. 20 C. in the followinginternal type developer (II) Grams Hydroquinone 15 Monomethylp-aminophenol sulfate 15 Anhydrous sodium sulfite 50 Potassium bromide10 Sodium hydroxide 25 Sodium thiosulfate 20. Water to 1 liter gives amaximum density at least 5 times the maximum density obtained when theequallyjexposed silver halide emulsion is developed for 4 minutes at 20C. in the following surface developer (I):

Grams pl-Hydroxyphenylglycine Sodium carbonate 100 Water to 1 liter anddeveloping only the unexposed portion of said emulsion layer in adeveloper containing a hydrazine compound of the general formula WhereR. is a mononuclear aryl radical.

3. The method of obtaining a direct positive image in a silver halideemulsion layer, which comprises exposing to light rays to which theemulsion is sensitive, a silver halide emulsion 5 layer a test portionof which upon exposure to a light intensity scale for a fixed timebetween /1o0 and 1 second and development. for 3 minutes at C. in thefollowing internal type developer (II):

Grams Hydroquinone 15 Monoethyl-p-amoniphenol sulfate 15 Anhydroussodium sulfite 50 Potassium bromide 10' Sodium hydroxide Sodiumthiosulfate 20 Water to 1 liter gives a maximum density at least 5 timesthe maximum density obtained when the equally exposed silver halideemulsion is developed for 4 minutes at 20 C. in the following surfacedeveloper (I):

Grams p-Hydroxyphenylglycine 10 Sodium carbonate 100 Water to 1 literand developing only the unexposed portion of said emulsion layer in adeveloper containing phenylhydrazine hydrochloride.

4. The method of obtaining a direct positive image in a silver halideemulsion layer, which comprises exposing to light rays to which theemulsion is sensitive, a silver halide emulsion layer a test portion ofwhich upon exposure to a light intensity scale for a fixed time between/100 and 1 second and development for 3 minutes at 20 C. in thefollowing internal type developer (II):

posed silver halide emulsion is developed for 4 minutes at 20 C. in thefollowing surface developer (I):

Grams p-Hydroxyphenylglycine 10 Sodium carbonate 100 Water to 1 literGrams Hydroquinone 15 Monomethyl-p-aminophenol sulfate 15 Anhydroussodium sulfite 50 Potassium bromide 10 Sodium hydroxide 25 Sodiumthiosulfate 20 Water to 1 liter gives a maximum density at least 5 timesthe maximum density obtained when the equally exposed silver halideemulsion is developed for 4 minutes at 20 C. in the following surfacedeveloper (I):

,. Grams p-Hydroxyphenylglycine 10 Sodium carbonate 100 Water to 1 literand developing only the unexposed portion of said emulsion layer in adeveloper containing p- [5 (methylsulfonamido) ethyllphenyl hydrazine.

6. The method of obtaining a direct positive image in a silver halideemulsion layer. which comprises exposing to light rays to which theemulsion is sensitive, a silver halide emulsion layer a test portion ofwhich upon exposure to a light intensity scale for a fixed time between/100 and 1 second and development for 3 minutes at 20 C. in thefollowing internal type developer (II):

Grams Hydroquinone 15 I Monomethyl-p-aminophenol sulfate 15 Anhydroussodium sulfite 50 Potassium bromide 10 Sodium hydroxide 25 Sodiumthiosulfate 20 Grams Hydroquinone 1'5! Monomethyl-p-aminophenol sulfate15 V Anhydrous sodium sulfite 50 Potassium bromide 10 Sodium hydroxide25 Sodium thiosulfate 20 Water to 1 liter gives a maximum density atleast 5 times the 'maximum density obtained when the equally ex- Waterto 1 liter gives a maximum density at least 5 times the maximum densityobtained when the equally'exposed silver halide emulsion is developedfor 4 minutesat 20 C. in the following surface developer (I) v Gramsp-I-Iydroxyphenylglycine 10 Sodium carbonate Water to 1 liter anddeveloping only the unexposed portion of said emulsion layer in adeveloper containing pphenylene disemicarbazide. I

'7. The method of obtaining a direct positive image in a silver halideemulsion layer, which comprises exposing to light rays to which theemulsion is sensitive, a silver halide emulsion layer a test portion ofwhich upon exposure to a light intensity scale for a fixed time between/100 and 1 second and develoment for 3 minutes at 20 C. in the followinginternal type developer (II) Grams Hydroquinone 15Monomethyl-p-aminophenol sulfate l5 Anhydrous sodium sulfite 50Potassium bromide 10 Sodium hydroxide 25 Sodium thiosulfate 20 Water to1 liter gives a maximum density at least 5 times the maximum densityobtained when the equally exl0 posed silver halide emulsion is developedfor 4 minutes at 20 C. in the following surface developer (I):

Grams p-Hydroxyphenylglycine 10 Sodium carbonate 100 Water to 1 literand developing only the unexposed portion of said emulsion layer in adeveloper containing sodium sulfosuccinyl dihydrazide.

CHARLES E. IVES.

No references cited.

Certificate of Correction Patent No. 2,563,785 August 7 1951 CHARLES E.IVES It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction asfollows:

Column 7, line 38, for Monoethyl-p-amonipheno1 sulfate readMonomethyLp-aminophenol sulfate;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOffice.

Signed and sealed this 16th day of October, A. D. 1951.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

1. THE METHOD OF OBTAINING A DIRECT POSITIVE IMAGE IN A SILVER HALIDEEMULSION LAYER WHICH COMPRISES EXPOSING TO LIGHT RAYS TO WHICH THEEMULSION IS SENSITIVE, A SILVER HALIDE EMULSION LAYER A TEST PORTION OFWHICH UPON EXPOSURE TO A LIGHT INTENSITY SCALE FOR A FIXED TIME BETWEEN1/100 AND 1 SECOND AND DEVELOPMENT FOR 3 MINUTES AT 20* C. IN THEFOLLOWING INTERNAL TYPE DEVELOPER (II)